Apparently in the manufacturing of Mylar films they are heat-set to stabilize them as the last step. They will then exhibit no more than the specified amount of shrinkage as stated in the data specification sheets UNTIL exposed to the original heat-set temperature. So using the shrinkage rate from the data specification sheets to eliminate film types was in error on my part. ALL Mylar films will heat shrink. Its now just a matter of attempting to determine the particular films heat set temperture. Its critical the temperature a particular Mylar will heat shrink is NOT above the temperature failure level of the attachment tapes!!!

So LAZAIR... you were correct that the advertised shrinkage rates were not important. Those numbers only tell us the nomimal exhibited shrinkage when the material is exposed to heat below the heat-set temperature.

I need to go back over the list and reinstate some films as candidates...

The deeper I get into this Mylar issue Im beginning to arrive at the conclusion that there are multiple MYLARs that fit the bill with regards to a suitable covering material. Having learned that ALL Mylars have a capacity for heat shrinkability when the HEAT-SET temperature is reached or exceeded... that opened the up the candidate field greatly.

Its now more a preference of the films appearance... such as clear, very clear, super clear, high clarity, translucent etc. that will further decide ones ultimate choice. The list I have created based on a criteria of film clarity, coatings, and thickness availability now numbers 21! Included in that list is a UV film... TeijinÆ TetoronÆ HB3. A super smooth polyester film with a UV absorbing agent, originally designed for green house applications. It has excellent weather-durability, low color and low haze. 2 mil or 3 mil is available. This particular film also has the lowest heat-set temperature at 300º F. The remainder of the candidates on my short list have a higher heat-set temperature of 374º F.

Thank you Steve.
Would it be possbile that the TED part of MYLAR now called TEDLAR would in fact be teflon ? Food for thought.

Lz

PS Tedlar® plastic coating has been a stalwart DuPont product since 1961, when the company introduced it for the booming construction industry. That year DuPont constructed a plant at its Buffalo, New York, site to manufacture the new polyvinyl fluoride (PVF) film. The weather-resistance of Tedlar® and its availability in several colors made it an attractive laminate for wood shutters, aluminum siding and many other housing applications. By the early 1970s Tedlar® applications had widened to include automobile trim. Ten years later it was being used as a surface laminate for flexible architectural structures like tents, canopies, outdoor pavilions and covered sports arenas. In the early 1990s Tedlar® surfacing appeared on flexible outdoor signs, banners and awnings. The chemical structure of Tedlar® makes it impermeable to dirt, oil and grit, so a good rainstorm will serve to keep it clean. It also resists penetration by the sun's ultraviolet radiation, thereby offering protection against discoloration and sun damage. Tedlar® continues to appear in new applications such as airplane and train interior surfaces, truck trailer sides and building panels.

My personal opinion is this. First choice for covering is Tedlar. All around it is the best covering for all the logical reasons.. it is light, durable ect.. ect.
Fabric is an alternative but to do it right it costs more and the process is far more complex considering all the paint work.

i noticed on the world news last night that the temp in Canada is around minus 3 deg c which means it is possibly snowing so all those keen types still flying how about a video or two i'm keen to see a lazair flying on skis thanks ozzie

Well... I finally found a supplier for one of the many films I have been looking for. It's MELINEX 516 PET film (Mylar)... a direct replacement film for MYLAR D film which DuPont has discontinued. This particular Melinex film is non-treated and has a very high clairty. I found it in a 60 inch width and in 100 and 250 ft rolls depending on which thickness you desire. As an example...